Infection regulates pro-resolving mediators that lower antibiotic requirements

Area of Science:

• Immunology
• Microbiology
• Pharmacology

Background:

• Mechanisms of bacterial infection-induced inflammation resolution are poorly understood.
• Specialized pro-resolving mediators (SPMs) are implicated in inflammation resolution.
• The role of specific SPMs in bacterial infections requires further elucidation.

Purpose of the Study:

• To investigate the role of SPMs in resolving bacterial infections.
• To identify specific SPMs involved in Escherichia coli infections.
• To determine the therapeutic potential of SPMs in enhancing bacterial clearance and host survival.

Main Methods:

• Exudate leukocyte trafficking and mediator-metabololipidomics in murine peritoneal E. coli infections.
• Temporal identification of pro-inflammatory mediators and SPMs.
• In vitro assays with human neutrophils and macrophages to assess phagocytosis and gene regulation.
• In vivo studies evaluating the effects of SPMs on bacterial titers, hypothermia, survival, and antibiotic efficacy.

Main Results:

• Resolvin (Rv) D5 and protectin D1 (PD1) were identified as dominant SPMs in self-resolving E. coli infections.
• Higher levels of RvD1 and PD1 were observed in germ-free mice compared to conventional mice.
• RvD1 and RvD5 reduced bacterial load, hypothermia, and increased survival in E. coli infections.
• RvD1, RvD5, and PD1 enhanced phagocytosis of E. coli by human immune cells.
• RvD5 counter-regulated pro-inflammatory genes (NF-κB, TNF-α) and activated the GPR32 receptor.
• SPMs accelerated infection resolution and enhanced antibiotic efficacy (ciprofloxacin, vancomycin) against E. coli and Staphylococcus aureus.

Conclusions:

• Specific SPMs are differentially regulated during bacterial infections and actively promote resolution.
• SPMs possess anti-phlogistic properties, enhance bacterial containment, and reduce antibiotic requirements.
• Host-directed SPM therapy holds promise for improving outcomes in bacterial infections and complementing antibiotic treatments.